What's the best way to group lines in poetry?

Okay, any experienced poet knows that this is a trick question. The best way is the way that works best for the poet and the audience. The line is the primary structural
element in poetry. It is the building block, just as the sentence is in prose. And while your poems may use sentences, it is how they are arranged in lines that helps to make them poems. The beginning poet
needs to experiment, both with line breaks and with the grouping of lines. In less formal poetry, such as free verse, a group of lines is like a paragraph in prose. It encapsulates one idea, one image, or one
set of actions.

In formal poetry, the stanza is often strictly fixed and defined, and poets will use enjambment in lines or even stanzas to break the boundaries of the form or tie stanzas together.

For the poet, the use of line and section is the same as sentence and paragraph in prose. They are the primary tools the poet has to build from. Or maybe a better analogy is that they are the lumber.
Measure twice. Cut once. Your lines should neither be too long or too short. Your sections should mainly be grouped for coherence. It is like the octet and sestet of the sonnet. They are separate
sections with a pivot of thought in between. This is why they are often separated on the page.